Electrical power is supplied to an electric motor from a supplying net through current supply cables. At their first end, current supply cables are connected to a centre supplying the electric motor and the second end is connected to the electric motor. A connection to the electric motor is typically carried out in a junction box of the electric motor. The ends of phase leads coupled to the windings of the electric motor stator are led to the junction box, and the current supply cables are coupled to these ends when connected. Depending on the purpose of use, the electric motor is connected to the supplying net by means of a star or a delta connection, i.e. Y or D connection. Depending on the connection manner, the connection of the current supply cables in the junction box of the electric motor is different, and the connection manner is typically selected by mounting connection base elements, i.e. circuit plates, of the junction box according to the Y or D connection.
A prior art connection base consists of a base made of an insulating material, such as plastic, and the bottom surface of the base is coupled to a metallic mounting flange to fasten it to the electric motor, or the base is fastened directly to the bottom of the junction box of the electric motor. The top surface of the plastic base is coupled to roughly U-shaped copper terminals, a three-phase electric motor typically comprising six terminals of that kind. The U-shaped terminal is bent at an angle of 90 degrees. The terminals are arranged on the base so that there are three terminals side by side in two rows, whereby the bases of the U-shaped terminals are against each other. One arm of a terminal is connected to the plastic base by means of a screw connection, for instance. In this case, a counterpart, which receives the screw, has been embedded or cast in the plastic base at its manufacturing stage. The other arm of the U-shaped terminal is connected to a current supply cable of a supplying phase typically by means of a cable lug connection. Thus, the cable lug is tightened to the terminal arm typically by a screw-nut fastening. The phase lead of the winding is connected to the base of the U-shaped terminal in the corresponding connection manner. The arms of the U-shaped terminal, to which the current supply conductors are connected, are also bent at a certain angle towards the centre point of the U-shape.
Such a prior art connection base is, however, associated with a problem. The connection base requires three fastening means, typically screw-nut combinations, for each terminal. The first fastening means is for fastening the terminal to the base, the second for fastening the phase lead to the terminal and the third for fastening the current supply cable to the terminal. Thus, three joint surfaces and three fastening means are required in the terminal. In addition, at the manufacturing stage of the connection base, fastening means, such as screw-receiving components which have to be manually set to the mould at the manufacturing stage, must be embedded in the plastic base of the connection base. Thus, the manufacture of the base is cumbersome and the price of the connection base is disadvantageous.